Comparison of Oil Recovery by Low Salinity Waterflooding in Secondary and Tertiary Recovery Modes

Author(s):  
Pubudu Hasanka Siyambalagoda Gamage ◽  
Geoffrey D. Thyne
Author(s):  
M. Fouad Snosy ◽  
Mahmoud Abu El Ela ◽  
Ahmed El-Banbi ◽  
Helmy Sayyouh

AbstractWaterflooding has been practiced as a secondary recovery mechanism for many years with no regard to the composition of the injected brine. However, in the last decade, there has been an interest to understand the impact of the injected water composition and the low salinity waterflooding (LSWF) in oil recovery. LSWF has been investigated through various laboratory tests as a promising method for improving oil recovery in carbonate reservoirs. These experiments showed diverse mechanisms and results. In this study, a comprehensive review and analysis for results of more than 300 carbonate core flood experiments from published work were performed to investigate the effects of several parameters (injected water, oil, and rock properties along with the temperature) on oil recovery from carbonate rock. The analysis of the results showed that the water composition is the key parameter for successful waterflooding (WF) projects in the carbonate rocks. However, the salinity value of the injected water seems to have a negligible effect on oil recovery in both secondary and tertiary recovery stages. The study indicated that waterflooding with optimum water composition can improve oil recovery up to 30% of the original oil in place. In addition, the investigation showed that changing water salinity from LSWF to high salinity waterflooding can lead to an incremental oil recovery of up to 18% in the tertiary recovery stage. It was evident that applying the optimum composition in the secondary recovery stage is more effective than applying it in the tertiary recovery stage. Furthermore, the key parameters of the injected water and rock properties in secondary and tertiary recovery stages were studied using Fractional Factorial Design. The results revealed that the concentrations of Mg2+, Na+, K+, and Cl− in the injected water are the greatest influence parameters in the secondary recovery stage. However, the most dominant parameters in the tertiary recovery stage are the rock minerals and the concentration of K+, HCO3−, and SO42− in the injected water. In addition, it appears that the anhydrite percentage in the carbonate reservoirs may be an effective parameter in the tertiary WF. Also, there are no clear relations between the incremental oil recovery and the oil properties (total acid number or total base number) in both secondary and tertiary recovery stages. In addition, the results of the analysis showed an incremental oil recovery in all ranges of the studied flooding temperatures. The findings of this study can help to establish guidelines for screening and designing optimum salinity and composition for WF projects in carbonate reservoirs.


AAPG Bulletin ◽  
2017 ◽  
Vol 101 (01) ◽  
pp. 1-18 ◽  
Author(s):  
Mark Person ◽  
John L. Wilson ◽  
Norman Morrow ◽  
Vincent E.A. Post

2018 ◽  
Vol 58 (2) ◽  
pp. 660
Author(s):  
A. Al-Sarihi ◽  
A. Zeinijahromi ◽  
P. Bedrikovetsky

Enhanced oil recovery by low-salinity waterflooding is considered to have positive results only when polar components exist in oil. This study shows that low-salinity brine can result in incremental recovery for non-polar oil through fines-assisted waterflooding. Despite the traditional view of fines migration that it should be avoided because of its detrimental effect on reservoir permeability, this work shows that permeability decline is a main mechanism in the low-salinity effect on non-polar oil. Laboratory coreflood tests were performed on a clay-rich Berea outcrop core and a clean sand core to investigate the effect of clay migration when the core is saturated with non-polar oil. The results show that fines migration reduces residual saturation by 18%. In addition, a decrease in the water volume production was observed due to the decrease in water relative permeability.


Author(s):  
Tao Zhang ◽  
Yiteng Li ◽  
Chenguang Li ◽  
Shuyu Sun

The past decades have witnessed a rapid development of enhanced oil recovery techniques, among which the effect of salinity has become a very attractive topic due to its significant advantages on environmental protection and economical benefits. Numerous studies have been reported focusing on analysis of the mechanisms behind low salinity waterflooding in order to better design the injected salinity under various working conditions and reservoir properties. However, the effect of injection salinity on pipeline scaling has not been widely studied, but this mechanism is important to gathering, transportation and storage for petroleum industry. In this paper, an exhaustive literature review is conducted to summarize several well-recognized and widely accepted mechanisms, including fine migration, wettability alteration, double layer expansion, and multicomponent ion exchange. These mechanisms can be correlated with each other, and certain combined effects may be defined as other mechanisms. In order to mathematically model and numerically describe the fluid behaviors in injection pipelines considering injection salinity, an exploratory phase-field model is presented to simulate the multiphase flow in injection pipeline where scale formation may take place. The effect of injection salinity is represented by the scaling tendency to describe the possibility of scale formation when the scaling species are attached to the scaled structure. It can be easily referred from the simulation result that flow and scaling conditions are significantly affected if a salinity-dependent scaling tendency is considered. Thus, this mechanism should be taken into account in the design of injection process if a sustainable exploitation technique is applied by using purified production water as injection fluid. Finally, remarks and suggestions are provided based on our extensive review and preliminary investigation, to help inspire the future discussions.


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